System and method for communication between RFID interrogators

ABSTRACT

One embodiment of the present invention sets forth a technique for efficiently interconnecting RFID interrogator elements. Each interrogator element is configured to function as both an RFID interrogator and an RFID tag. The RFID interrogator function enables one interrogator element to perform a read or write data operation to a second interrogator element functioning as an RFID tag. Two-way communications between interrogator elements is facilitated by read and write operations. A data backhaul network may be advantageously implemented as a wireless mesh network, comprising a plurality of interrogator elements, to transmit data from each interrogator element to a server for processing.

BACKGROUND

Technical Field

Embodiments of the present invention relate generally to wirelessdigital communication systems and, more specifically, to a system andmethod for communication between radio frequency identifier (RFID)interrogators.

Description of the Related Art

A radio frequency identifier (RFID) network typically includes aplurality of RFID interrogators, each configured to read data fromcertain RFID tags that are positioned in sufficiently close proximity.This data is then conventionally transmitted upstream via a backhaulnetwork to a server configured to process the data or log the data forlater processing. Each RFID tag is configured to store certain data,which may comprise read-only, writeable, or measured data. For example,an RFID tag may store a product code or serial number for an associatedarticle of manufacture. An RFID interrogator retrieves data storedwithin the RFID tag via a radio frequency (RF) communicationtransaction.

Certain RFID tags are referred to as “passive,” and typically deriveoperating power by harvesting ambient RF energy. When the RFIDinterrogator attempts to read a passive RFID tag, sufficient ambient RFenergy is provided to the passive RFID tag to power up and operate. Totransmit stored data to the RFID interrogator, passive RFID tagstypically employ backscatter techniques, which modulate reflected RFenergy originating from the RFID interrogator. Certain other RFID tagsare referred to as “active,” and typically derive operating power from abattery or other robust power source. To transmit stored data to theRFID interrogator, active RFID tags typically generate a modulated RFsignal. In both cases, the RFID interrogator conventionally transmitsdata to the RFID tag, and the RFID tag transmits stored data back to theRFID interrogator. In both cases, RFID interrogators are typicallyconfigured to avoid interference with each other, for example byremaining inactive while nearby RFID interrogators transmit RF energy toperform read transactions with associated RFID tags.

One challenge in deploying an RFID network is implementing the backhaulnetwork, which must be connected to each RFID interrogator. One approachto implementing the backhaul network involves coupling a wired datanetwork, such as a wired Ethernet network, to each RFID interrogator.Implementing a conventional wired backhaul network for the RFIDinterrogators is generally expensive and complex, with each differentRFID interrogator requiring that a separate cable be routed and coupledto the RFID interrogator from a wired data switch. Alternatively, thebackhaul network may be conventionally implemented using a standardwireless data networking technology, such as the industry standard“WiFi” or related technologies. Implementing a backhaul network usingconventional wireless data networking technologies generally eliminatesmuch of the cost and complexity associated with a wired data network,but introduces different problems, such as potential interference fromother legitimate users of the wireless data networking technology.

As the foregoing illustrates, what is needed in the art is a moreefficient technique for interconnecting RFID interrogators.

SUMMARY

One embodiment of the present invention sets forth acomputer-implemented method for transmitting and receiving data via aradio signal, the method comprising: transmitting a first interrogationrequest to a first radio frequency identifier (RFID) device, receiving afirst interrogation reply from the first RFID device, receiving a secondinterrogation request from a second RFID device, and transmitting asecond interrogation reply to the second RFID device in response to thesecond interrogation request.

Other embodiments include, without limitation, a computer-readablemedium that includes instructions that enable a processing unit toimplement one or more aspects of the disclosed methods as well as asystem configured to implement one or more aspects of the disclosedmethods.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A illustrates a wireless network, configured to implement one ormore aspects of the present invention;

FIG. 1B illustrates an interrogator element configured to operate withinthe wireless network of FIG. 1A, according to one embodiment of theinvention;

FIG. 2 illustrates a digital radio transceiver configured to implementone or more aspects of the present invention;

FIG. 3A is a flow diagram of a method for bidirectional communicationperformed by an interrogator element, according to one embodiment of theinvention; and

FIG. 3B is a flow diagram of a method for bidirectional communicationperformed by an interrogator element, according to one embodiment of theinvention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a more thorough understanding of the present invention. However,it will be apparent to one of skill in the art that the presentinvention may be practiced without one or more of these specificdetails. In other instances, well-known features have not been describedin order to avoid obscuring the present invention.

FIG. 1A illustrates a wireless network 100, configured to implement oneor more aspects of the present invention. The wireless network 100includes interrogator elements 120 configured to both communicate withtag elements 110 and present as tags to other interrogator elements 120.For example interrogator element 120-1 may interrogate tag elements110-1 and 110-2 via communications links 122-1 and 122-2, respectively.Each communications link 122 implements an RFID communications protocolemploying a certain RF channel, or channels, and appropriate modulationtechniques. The RFID communications protocol may also specify a specificrange of frequencies organized as available RFID channels. Interrogatorelement 120-1 may also interrogate interrogator element 120-2,configured to temporarily operate as an RFID tag, via communicationslink 124-1. Similarly, interrogator element 120-2 may interrogateinterrogator element 120-1, also configured to temporarily operate as anRFID tag. In one embodiment, communications links 124 operate withinavailable RFID channels to implement a substantially identical RFIDprotocol as that implemented for communications links 122. In analternative embodiment, communications links 124 implement a differentprotocol than the RFID protocol, for example to facilitate higherperformance communications than enabled within the RFID protocol, butstill utilizing an available RFID channel and adhering to regulatoryrequirements of the RFID channel.

Certain passive RFID tags utilize a backscatter modulation technique inwhich an interrogator element 120 transmits significantly more energythan an amount of backscatter energy received back from a tag element110. The ratio of transmitted energy versus backscattered energy may bemany orders of magnitude in some settings. Receiver sensitivitylimitations and regulations defining maximum transmission power levelsfor RFID interrogators together limit a maximum distance from aninterrogator element 120 to a tag element 110.

However, an interrogator element 120 configured to transmit data withinmaximum transmission power levels over an RFID channel may be locatedrelatively far away from another interrogator element 120 configured toreceive the data. Furthermore, two interrogator elements 120, each withan independent power source and each able to generate a unique RF signalfor transmission, may be located relatively far apart compared to themaximum distance between an interrogator element 120 and a tag element110 while achieving two-way communication and operating within themaximum transmission power level. Certain active RFID tags transmit asmall amount of energy relative to a companion interrogator, creating asimilar scenario, in which two interrogator elements 120 may be locatedrelatively far apart while achieving two-way communication.

In one embodiment, pairs of interrogator elements 120 within aninterrogator mesh network 130 are configured to perform two-waycommunications by taking turns alternately operating as either an RFIDreader or an RFID tag. With two-way communication between interrogatorelements 120, data may be routed between arbitrary source anddestination interrogator elements 120 within interrogator mesh network130. In an alternative embodiment, pairs of interrogator elements 120achieve two-way communication within the interrogator mesh network 130by transmitting data to each other via one or more RFID channels andwithin maximum transmission power levels, but without specific regard toRFID protocols.

One or more interrogator elements 120 may be coupled to an accessnetwork 140, providing access to interrogator elements 120. For example,interrogator element 120-3 may be coupled to an access network 130 viaone or more suitable technologies, such as the technologies known in theart as wired Ethernet, WiFi, Bluetooth, or ZigBee.

FIG. 1B illustrates an interrogator element 120 configured to operatewithin the wireless network 100 of FIG. 1A, according to one embodimentof the invention. The interrogator element 120 comprises a processingunit 160, a digital radio subsystem 162, a power subsystem 164, anantenna 166, a non-volatile memory 154, and volatile memory 156. Certainembodiments also comprise one or more additional elements, such as ametrology subsystem 150, a control subsystem 152, and a local areanetwork (LAN) interface 158.

Processing unit 160 includes a processor core configured to retrieve andexecute programming instructions from non-volatile memory 154. Duringthe course of executing the programming instructions, the processor coremay also store and retrieve data residing within the volatile memory156. Digital radio subsystem 162 comprises a radio receiver circuitconfigured to demodulate and digitize incoming RF electrical signals.Digital radio subsystem 162 also comprises a radio transmitter circuitconfigured to modulate a digital signal to generate RF electricalsignals for transmission. Antenna 166 converts incident electromagneticenergy into the incoming RF electrical signals and also converts the RFelectrical signals for transmission into radiated electromagneticenergy. Power subsystem 164 comprises regulation and power conversioncircuitry configured to provide electrical voltage sources to eachcircuit and subsystem within the interrogator element 120. Powersubsystem 164 may also include an energy source such as a photovoltaicsystem, a battery or fuel cell. In one embodiment, LAN interface 158includes circuitry to implement wired Ethernet, WiFi, Bluetooth, orZigBee, or any combination thereof.

Metrology subsystem 150 comprises circuitry configured to perform one ormore measurements, such as voltage, current, power, accumulated power,flow rate, accumulated flow, temperature, humidity, vibration, or anyother quantifiable physical value or metric. Metrology subsystem 150quantizes measured results into a digital value for processing andstorage by processing unit 160. In one embodiment, metrology subsystem150 comprises a power meter for measuring accumulated utilization ofpower. The control system 152 comprises one or more switches forcontrolling electrical signals. In one embodiment, control system 152 isa power switch for turning electrical power on or off.

FIG. 2 illustrates a digital radio transceiver 200 configured toimplement one or more aspects of the present invention. In oneembodiment, digital radio transceiver 200 implements digital radiosubsystem 162 of FIG. 1B. In another embodiment, digital radiotransceiver 200 implements digital radio subsystem 162, MPU 210implements processing unit 160, and memory 212 implements one or both ofnon-volatile memory 154 and volatile memory 156.

The digital radio transceiver 200 may include, without limitation, amicroprocessor unit (MPU) 210, a digital signal processor (DSP) 214,digital to analog converters (DACs) 220, 221, analog to digitalconverters (ADCs) 222, 223, analog mixers 224, 225, 226, 227, a phaseshifter 232, an oscillator 230, a power amplifier (PA) 242, a low noiseamplifier (LNA) 240, an antenna switch 244, and an antenna 246. A memory212 may be coupled to the MPU 210 for local program and data storage.Similarly, a memory 216 may be coupled to the DSP 214 for local programand data storage.

In one embodiment, the MPU 210 implements procedures for processing IPpackets transmitted or received as payload data by the digital radiotransceiver 200. The procedures for processing the IP packets mayinclude, without limitation, wireless routing, encryption,authentication, protocol translation, and routing between and amongdifferent wireless and wired network ports.

The DSP 214 implements signal processing procedures for modulating aserialized representation of payload data comprising packets, such as IPpackets or RFID protocol data, for wireless transmission, for examplewithin the frequency range of available RFID channels. The serializedrepresentation may encode one or more bits of payload data permodulation symbol or less than one bit per modulation symbol. A receivermay demodulate each modulation symbol to recover the one or more bits ofpayload data. In one embodiment the one or more bits of payload data areused to generate a corresponding IP packet. In another embodiment, theone or more bits of payload data are used to form an RFID interrogationmessage or an RFID interrogation response message.

The DSP 214 may also implement multi-channel modulation for simultaneoustransmission of independent units of payload data via multiple,independent channels. Each independent channel occupies a differentfrequency range in a frequency domain representation of a transmittedradio signal. The DSP 214 also implements signal processing proceduresfor receiving payload data. The procedures may include, withoutlimitation filtering, energy detection, signal characterization, andsimultaneous demodulation of multiple, independent channels.

In one embodiment, the DSP 214 is configured to modulate data within agiven channel using a particular modulation technique that is selectedform a set of different modulation techniques, based on prevailingchannel requirements. For a given packet of data, a particulartransmission bit rate may be implemented using one of the differentmodulation techniques, based on channel conditions. For example, if aselected channel is subjected to a relatively large amount of noise,then a lower bit rate modulation technique that is more tolerant ofnoise may be selected. Alternatively, if a selected channel is subjectedto relatively low noise and low loss, then a higher bit rate modulationtechnique may be selected despite a potentially reduced noise tolerance.Exemplary modulation techniques known in the art include, withoutlimitation, frequency shift keying (FSK) and quadrature amplitudemodulation (QAM). FSK may be implemented as a robust, but relatively lowbit rate technique for representing one or more bits of data permodulation symbol as signal energy in at least one of two or moredefined frequency bands. QAM may be implemented as a relatively high bitrate technique for representing a set of two or more bits per modulationsymbol within an amplitude-phase space. Each possible value representedby the two or more bits is mapped to a unique region within theamplitude-phase space. A collection of regions within theamplitude-phase space is known as a constellation. During modulation,each set of two or more bits comprising a modulation symbol is encodedand mapped to an appropriate region within a correspondingconstellation. Persons skilled in the art will understand thatquadrature encoded signal pairs may be used to conveniently implementQAM modulation. Furthermore, any technically feasible modulation,demodulation, filtering, energy detection, and signal characterizationtechniques may be implemented by the DSP 214 without departing the scopeand spirit of embodiments of the present invention.

The DSP 214 is coupled to DAC 220 and DAC 221. Each DAC 220, 221 isconfigured to convert a stream of outbound digital values into acorresponding analog signal. The outbound digital values are computed bythe signal processing procedures for modulating one or more channels.The DSP 214 is also coupled to ADC 222 and ADC 223. Each ADC 222, 223 isconfigured to sample and quantize an analog signal to generate a streamof inbound digital values. The inbound digital values are processed bythe signal processing procedures to demodulate and extract payload datafrom the inbound digital values.

In one embodiment, the DSP 214 generates two modulated streams ofoutbound digital values, which are converted to corresponding analogquadrature signals by DACs 220, 221. The analog quadrature signals areseparately mixed with a radio frequency (RF) carrier signal by analogmixers 224, 225 to generate corresponding quadrature RF signals, eachhaving a frequency domain image centered about the frequency of the RFcarrier signal. Oscillator 230 generates the RF carrier signal and phaseshifter 232 generates a 90-degree shifted representation of the RFcarrier signal for generating quadrature RF signals. The PA 242 combinesthe quadrature RF signals to generate a modulated RF signal, which iscoupled through the antenna switch 244 to the antenna 246. The antenna246 converts the modulated RF signal from an electrical representationto an electromagnetic representation for wireless transmission. Thewireless transmission may be directed to a different instance of thedigital radio transceiver 200, residing within a different node of thewireless mesh network 102.

When the digital radio transceiver 200 is receiving data, the antenna246 converts an incoming electromagnetic RF signal to an electrical RFsignal, which is coupled through the antenna switch 244 to the LNA 240.The LNA 240 amplifies the electrical RF signal and couples the amplifiedRF signal to analog mixers 226 and 227. The amplified RF signal ischaracterized as having a signal image centered about an RF carrierfrequency. The analog mixer 227 shifts the signal image down infrequency to an in-phase baseband component of the signal image. Thesignal is in-phase with respect to the RF carrier signal generated byoscillator 230. The analog mixer 226 shifts the signal image down infrequency to a 90-degree shifted baseband component of the signal image.The in-phase and 90-degree shifted baseband signals comprise aquadrature representation of one or more channels within the electricalRF signal. A plurality of different frequency channels may berepresented within the baseband signals. The DSP 214 is configured tomap the stream of inbound digital values, comprising a time domainrepresentation of the baseband signals, to a frequency domainrepresentation of the baseband signals. Persons skilled in the art willrecognize that the frequency domain representation may be used toefficiently isolate one data bearing signal within one channel from asignal within a different channel. Similarly, the frequency domainrepresentation may be used to detect noise and interfering transmissionswithin a given channel.

In one embodiment, the oscillator 230 can be programmed to generate oneselected frequency from a plurality of possible frequencies. Each of theplurality of frequencies corresponds to a different channel. Theselected frequency determines a center channel for a range of channelsthat are concurrently available for processing by the DSP 214 to receiveor transmit data. For example, if a frequency range of 4 MHz defines tenchannels, then each channel is allocated a bandwidth of 400 kHz. In thisexample, a frequency range of 2,000 kHz representing five channels isprocessed by the DSP 214 for transmitting or receiving data on one ormore of the five channels. If the oscillator 230 is programmed togenerate a different selected frequency, then a different set of fiveconcurrently available channels may be used for transmitting orreceiving data. The center channel may be changed arbitrarily byprogramming the oscillator 230 independently of the DSP 214 operating onthe concurrently available channels. The digital radio transceiver 200may be configured with an arbitrary number of concurrently availablechannels, each having an arbitrary bandwidth without departing the scopeand spirit of embodiments of the present invention.

FIG. 3A is a flow diagram of a method 300 for bidirectionalcommunication performed by an interrogator element, according to oneembodiment of the invention. Although the method steps are described inconjunction with the systems of FIGS. 1A, 1B and 2, persons skilled inthe art will understand that any system configured to perform the methodsteps, in any order, is within the scope of the present invention. Thismethod 300 may be performed by the interrogator element 120 of FIG. 1A.

The method 300 begins in step 310, where the interrogator element 120transmits an interrogation request to a first RF ID device. In oneembodiment, the interrogation request is structured according to anytechnically feasible RFID protocol, such as the well-known ISO 15693, orISO 18000-7 protocols. In another embodiment, the interrogation requestis structured according to a standard short-distance data protocol suchas the well-known IEEE 802.11 (WiFi) standards or IEEE 802.15(Bluetooth) standards. Prior to transmitting the interrogation request,the interrogator element 120 may configure the digital radio subsystem162 of FIG. 1B to operate according to a particular protocol and on aselected frequency, for example within an available RFID channel. Theinterrogation request may comprise a read request to retrieve data fromthe first RFID device or a write request to transmit data to the RFIDdevice. In step 312, the interrogator element 120 receives aninterrogation reply from the first RFID device. The interrogation replymay include data from the interrogation element 120 or confirmation thata write operation was successful. In one embodiment, the interrogationreply conforms to the protocol of the interrogation request. Afterreceiving the interrogation reply, the interrogator element 120 mayconfigure the digital radio subsystem 162 to operate in a mode that isreceptive to an incoming interrogation request.

In step 314, the interrogator element 120 receives an interrogationrequest from a second RFID device. In one embodiment, the interrogationrequest is structured according to an RFID protocol. The interrogationrequest may comprise a read request to retrieve data within theinterrogator element 120 or a write request to transmit data to theinterrogator element 120. In step 316, the interrogation element 120replies to the interrogation request from the second RFID device inaccordance with protocol requirements of the interrogation request. Thereply may comprise data from the interrogator element 120 orconfirmation that a write operation was successful within theinterrogator element 120. The method 300 terminates in step 316.

In one embodiment, the first RFID device comprises an RFID tag, such astag element 110, and the second RFID device comprises a differentinterrogator element 120. In this embodiment, interrogator element 120-1may perform method steps 310 and 312 to read a first set of data fromtag element 110-1, and method steps 314 and 316 to transmit a second setof data to interrogator element 120-2. The second set of data mayinclude the first set of data or a derivative thereof.

In another embodiment, the first RFID device and the second RFID deviceboth comprise interrogator elements 120. For example, interrogatorelement 120-2 may perform method steps 310 and 312 to read a first setof data from interrogator element 120-1 and method steps 314 and 316 totransmit a second set of data to interrogator element 120-3. The secondset of data may include the first set of data or a derivative thereof.Alternatively, the interrogator element 120-2 may perform method steps310 and 312 to write a first set of data to interrogator element 120-1and method steps 314 and 316 to receive a second set of data frominterrogator element 120-3. Persons skilled in the art will recognizethat data may be pushed from one interrogator element 120 to anotherusing a write mechanism or pulled from one interrogator element 120 toanother using a read mechanism. Both read and write mechanisms ofcommunication with RFID tags are known in the art and may beadvantageously combined in certain embodiments of the present invention.

In yet another embodiment, the first RFID device and the second RFIDdevice comprise the same type of device, such as interrogator device120, configured to operate as both an RFID interrogator and an RFID tag.The method steps 310 through 316 may be performed for two-waycommunication between the two interrogator devices 120.

FIG. 3B is a flow diagram of a method 302 for bidirectionalcommunication performed by an interrogator element, according to oneembodiment of the invention. Although the method steps are described inconjunction with the systems of FIGS. 1A, 1B and 2, persons skilled inthe art will understand that any system configured to perform the methodsteps, in any order, is within the scope of the present invention. Thismethod 302 may be performed by the interrogator element 120 of FIG. 1A.

The method 302 begins in step 320, where the interrogator element 120receives an interrogation request from a first RF ID device. In oneembodiment, the interrogation request is structured according to anytechnically feasible RFID protocol, such as the well-known ISO 15693, orISO 18000-7 protocols. In another embodiment, the interrogation requestis structured according to a standard short-distance data protocol suchas the well-known IEEE 802.11 (WiFi) standards or IEEE 802.15(Bluetooth) standards. Prior to receiving the interrogation request, theinterrogator element 120 may configure the digital radio subsystem 162of FIG. 1B to operate according to a particular protocol and on aselected frequency, for example within an available RFID channel. Theinterrogation request may comprise a read request to retrieve data fromthe interrogator element 120 or a write request to transmit data to theinterrogator element 120.

In step 322, the interrogator element 120 replies to the interrogationrequest by transmitting an interrogation reply from the first RFIDdevice. In one embodiment, the interrogation reply conforms to theprotocol of the interrogation request. The interrogation reply mayinclude data from the interrogation element 120 or confirmation that awrite operation was successful within the interrogation element 120. Theinterrogator element 120 may configure the digital radio subsystem 162to confirm to a particular protocol, such as an RFID protocol, prior totransmitting the interrogation reply. After transmitting theinterrogation reply, the interrogator element 120 may configure thedigital radio subsystem 162 to operate in a mode that is receptive toanother incoming interrogation request.

In step 324, the interrogator element 120 transmits an interrogationrequest to a second RFID device. In one embodiment, the interrogationrequest is structured according to an RFID protocol. The interrogationrequest may comprise a read request to retrieve data within the secondRFID device or a write request to transmit data to the second RFIDdevice. In step 326, the interrogation element 120 replies to theinterrogation request from the second RFID device in accordance withprotocol requirements of the interrogation request. The reply maycomprise data from the second RFID device or confirmation that a writeoperation was successful within the second RFID device. The method 302terminates in step 326.

In one embodiment, the first RFID device and the second RFID device bothcomprise interrogator elements 120. For example, interrogator element120-2 may perform method steps 320 and 322 to receive a first set ofdata from interrogator element 120-1 and method steps 314 and 316 totransmit a second set of data to interrogator element 120-3. The secondset of data may include the first set of data or a derivative thereof.Alternatively, the interrogator element 120-2 may perform method steps310 and 312 to transmit a first set of data to interrogator element120-1 and method steps 314 and 316 to receive a second set of data frominterrogator element 120-3. Persons skilled in the art will recognizethat data may be pushed from one interrogator element 120 to anotherusing a write mechanism or pulled from one interrogator element 120 toanother using a read mechanism. Both read and write mechanisms ofcommunication with RFID tags are known in the art and may beadvantageously combined in certain embodiments of the present invention.

In another embodiment, the first RFID device comprises interrogatorelement 120-2, and the second RFID device comprises tag element 110-1.In this embodiment, interrogator element 120-1 may perform method steps320 and 322 to receive a first set of data from interrogator element120-2, and method steps 324 and 326 to read a second set of data fromtag element 110-1.

In yet another embodiment, the first RFID device and the second RFIDdevice comprise the same device, such as another interrogator device120. The method steps 320 through 326 may be performed for two-waycommunication between the two interrogator devices 120.

In certain embodiments, the interrogator element 120 implements a powermeter configured to measure accumulated power consumption and report theaccumulated power consumption via the interrogator mesh network 130 ofFIG. 1A to a server coupled to the access network 140. In suchembodiments, each interrogator element 120 may operate independently tomeasure a corresponding sample of accumulated power consumption andreport the sample of accumulated power consumption via a push regime ora pull regime, or a combination thereof through the interrogator meshnetwork 130. In this way, accumulated power consumption samples for allinterrogator elements 120 may be gathered by the server.

In sum, a technique for implementing two-way communication betweeninterrogator elements in a wireless network is disclosed. Aninterrogator element is configured to operate as both an RFID reader andan RFID tag to achieve two-way communication with a differentinterrogator element. Each interrogator element may participate in aninterrogator mesh network configured to route data between theparticipating interrogator elements. Each interrogator element may alsoact as a conventional RFID interrogator that communicates with RFID tagdevices.

One advantage of the disclosed systems and methods is that a backhaulnetwork that interconnects RFID interrogators may be efficientlyimplemented by combining interrogator and tag behavior within a singleinterrogator element device.

While the forgoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof. For example, aspects of thepresent invention may be implemented in hardware or software or in acombination of hardware and software. One embodiment of the inventionmay be implemented as a program product for use with a computer system.The program(s) of the program product define functions of theembodiments (including the methods described herein) and can becontained on a variety of computer-readable storage media. Illustrativecomputer-readable storage media include, but are not limited to: (i)non-writable storage media (e.g., read-only memory devices within acomputer such as CD-ROM disks readable by a CD-ROM drive, flash memory,ROM chips or any type of solid-state non-volatile semiconductor memory)on which information is permanently stored; and (ii) writable storagemedia (e.g., floppy disks within a diskette drive or hard-disk drive orany type of solid-state random-access semiconductor memory) on whichalterable information is stored. Such computer-readable storage media,when carrying computer-readable instructions that direct the functionsof the present invention, are embodiments of the present invention.

In view of the foregoing, the scope of the present invention isdetermined by the claims that follow.

I claim:
 1. A computer-implemented method for transmitting and receivingdata via a radio signal, the method comprising: transmitting, via afirst channel included in a plurality of available channels that aregenerated concurrently by a digital radio transceiver, a firstinterrogation request to a first radio frequency identifier (RFID) tagdevice according to an RFID communication protocol that specifies arange of frequencies organized as available RFID channels; receiving,via a second channel included in the plurality of available channels, afirst interrogation reply transmitted from the first RFID tag deviceaccording to the RFID communication protocol; and with respect to eachRFID interrogator device included in a plurality of RFID interrogatordevices in an interrogator network, transmitting, via any currentlyavailable channel included in the plurality of available channels, datato the RFID interrogator device according to a second communicationprotocol, wherein the second communication protocol is different thanthe RFID communication protocol and adheres to a plurality of regulatoryrequirements associated with an available RFID channel.
 2. The method ofclaim 1, wherein the first interrogation request comprises a readrequest for a first set of data residing within the first RFID tagdevice, and the first interrogation reply comprises a first message thatincludes the first set of data.
 3. The method of claim 1, wherein thefirst interrogation request comprises a write request for a second setof data to be written to the first RFID tag device, and the firstinterrogation reply comprises a second message that confirms asuccessful write operation for the second set of data within the firstRFID tag device.
 4. The method of claim 1, wherein the data istransmitted in response to a read request.
 5. The method of claim 1,wherein the data is transmitted in response to a write request andconfirms a successful write operation.
 6. The method of claim 1, furthercomprising: receiving a second interrogation request from a third RFIDdevice; and transmitting a second interrogation reply to the third RFIDdevice in response to the third interrogation request.
 7. The method ofclaim 1, wherein the data comprises at least a portion of the firstinterrogation reply.
 8. The method of claim 2, wherein the first set ofdata comprises metrology data measured by the first RFID tag device. 9.The method of claim 8, wherein the metrology data comprises accumulatedpower consumption data.
 10. The method of claim 1, wherein the firstRFID tag device comprises an interrogator element.
 11. A non-transitorycomputer-readable storage medium including instructions that, whenexecuted by a processing unit, cause the processing unit to transmit oneor more data packets via a radio signal by performing the steps:transmitting, via a first channel included in a plurality of availablechannels that are generated concurrently by a digital radio transceiver,a first interrogation request to a first radio frequency identifier(RFID) tag device according to an RFID communication protocol thatspecifies a range of frequencies organized as available RFID channels;receiving, via a second channel included in the plurality of availablechannels, a first interrogation reply transmitted from the first RFIDtag device according to the RFID communication protocol; and withrespect to each RFID interrogator device included in a plurality of RFIDinterrogator devices in an interrogator network, transmitting, via anycurrently available channel included in the plurality of availablechannels, data to the RFID interrogator device according to a secondcommunication protocol, wherein the second communication protocol isdifferent than the RFID communication protocol and adheres to aplurality of regulatory requirements associated with an available RFIDchannel.
 12. The non-transitory computer-readable storage medium ofclaim 11, wherein the first interrogation request comprises a readrequest for a first set of data residing within the first RFID tagdevice, and the first interrogation reply comprises a first message thatincludes the first set of data.
 13. The non-transitory computer-readablestorage medium of claim 11, wherein the first interrogation requestcomprises a write request for a second set of data to be written to thefirst RFID tag device, and the first interrogation reply comprises asecond message that confirms a successful write operation within thefirst RFID tag device.
 14. The non-transitory computer-readable storagemedium of claim 11, wherein the data is transmitted in response to aread request.
 15. The non-transitory computer-readable storage medium ofclaim 11, wherein the data is transmitted in response to a write requestand confirms a successful write operation.
 16. The non-transitorycomputer-readable storage medium of claim 11, further comprising:receiving a second interrogation request from a third RFID device; andtransmitting a second interrogation reply to the third RFID device inresponse to the second interrogation request.
 17. The non-transitorycomputer-readable storage medium of claim 11, wherein the data comprisesat least a portion of the first interrogation reply.
 18. Thenon-transitory computer-readable storage medium of claim 12, wherein thefirst set of data comprises accumulated power consumption data measuredby the first RFID tag device.
 19. The non-transitory computer-readablestorage medium of claim 11, wherein the first RFID tag device comprisesan interrogator element.
 20. A wireless network device, comprising: aradio transceiver circuit configured to generate a radio signal for datatransmission and to receive a signal for data reception; and aprocessing unit that is coupled to the radio transceiver circuit andconfigured to: transmit, via a first channel included in a plurality ofavailable channels that are generated concurrently by a digital radiotransceiver, a first interrogation request to a first radio frequencyidentifier (RFID) tag device according to an RFID communication protocolthat specifies a range of frequencies organized as available RFIDchannels; receive, via a second channel included in the plurality ofavailable channels, a first interrogation reply transmitted from thefirst RFID tag device according to the RFID communication protocol; andwith respect to each RFID interrogator device included in a plurality ofRFID interrogator devices in an interrogator network, transmit, via anycurrently available channel included in the plurality of availablechannels, data to the RFID interrogator device according to a secondcommunication protocol, wherein the second communication protocol isdifferent than the RFID communication protocol and adheres to aplurality of regulatory requirements associated with an available RFIDchannel.
 21. The wireless network device of claim 20, wherein the datacomprises accumulated power consumption data measured by the first RFIDtag device.
 22. The computer-implemented method of claim 1, wherein thesecond communication protocol affords higher performance communicationthan the RFID communication protocol.
 23. The non-transitorycomputer-readable medium of claim 11, wherein the second communicationprotocol affords higher performance communication than the RFIDcommunication protocol.
 24. The wireless network device of claim 20,wherein the second communication protocol affords higher performancecommunication than the RFID communication protocol.
 25. Thecomputer-implemented method of claim 1, wherein the data is transmittedto the RFID interrogator device via the second channel included in theplurality of available channels.
 26. The computer-implemented method ofclaim 1, wherein the data is received within the first interrogationreply according to the RFID protocol and on the first channel and thentransmitted to the RFID interrogator device according to the secondcommunication protocol and on the second channel.
 27. Thecomputer-implemented method of claim 1, further comprising changing theplurality of available channels by adjusting an oscillator, wherein theoscillator is adjusted independently of a digital signal processor thatoperates on the plurality of available channels.
 28. Thecomputer-implemented method of claim 1, wherein the currently availablechannel comprises the first channel.
 29. The computer-implemented methodof claim 1, wherein the currently available channel comprises the secondchannel.